The chemical and biochemical nature of a new class of neurons and neuroactive molecules, peptidergic neurons and peptide neurotransmitters, has been investigated. The solution conformations of enkephalins, ACTH, oxytocins and somatostatins are being elucidated using proton magnetic resonance spectroscopy. Neuropeptide fragments and the neurosecretory granules which contain them are being isolated to investigate the mode of biosynthesis, storage and secretion. Presynaptic and postsynaptic proteolytic enzymes are being isolated to investigate their role in triggering and termination events at peptidergic synapses.